Graco 257815 User manual

313768B
Repair Kit
Piston Repair Kit
257815
- For servicing the piston on FinishPro 290 sprayers -
NOTE: For proper compressor operation, you must also replace
the valve plate assembly (kit 257836) when replacing the piston.
Pressure Relief Procedure
Important Safety Instructions
For detailed instructions and warnings,
see sprayer manual.
To reduce the risk of injury from injection, always follow
this procedure when instructed to relieve pressure,
stop spraying, service equipment, or install or clean
spray tip.
1. Set power/function selection switch to OFF and
unplug sprayer.
2. Turn pressure knob to lowest setting.
3. Hold gun to side of grounded metal pail. Trigger the
gun to relieve pressure.
4. Turn prime valve to PRIME.
If you suspect spray tip or hose is completely clogged, or
that pressure has not been fully relieved after following
these steps, VERY SLOWLY loosen tip guard retaining
nut or hose end coupling to relieve pressure gradually,
then loosen completely. Clear tip or hose obstruction.
ti9346a
ti8943a

2313768B
Disassembly
1. Relieve Pressure (see cover) and unplug sprayer.
2. Remove shroud and compressor:
a. Loosen IEC cord clamp screw and remove IEC
plug from compressor.
b. Remove air hose from compressor and remove
outlet fitting from compressor.
c. Remove four screws. Tip compressor assembly
down and forward to remove from sprayer.
Place compressor on workbench.
d. Remove two screws and IEC cord clamp.
Remove two screws and compressor shroud.
3. Remove cooling tube (71) by loosening cooling tube
nuts (70).
4. Use 1/2 in. socket to remove three bolts (100) from
head (74).
5. Use flat-blade screwdriver to pry head (74) from top
of plate (75) and cylinder (76) from bottom of valve
plate (75).
6. Use 7/32 in. allen wrench to remove hex screw (87)
from piston rod (77).
ti13409a
ti13411a
ti13416a
ti13664a
ti13414a
ti13941a
100
74
75
76
71
70
70
ti13940a
87
77

313768B 3
Reassembly
1. Replace piston (77) and cylinder (76) and use 7/32
in. allen wrench to tighten hex screw (87) into piston
rod.
2. Replace valve plate (75) with ribs facing up toward
head.
3. Replace three bolts (100) and use 1/2 in. socket to
tighten into head (74). Torque all three bolts to 75
in-lb, then torque all bolts again to 210 in-lb.
4. Replace cooling tube (71) by tightening cooling tube
nuts (70).
5. Replace Compressor and shroud:
a. Install compressor shroud with two screws.
Install IEC cord clamp with two screws.
b. Install air inlet fitting.
c. Tip compressor assembly up and back into
frame. Install four screws.
d. Install IEC connector and tighten cord clamp.
Install air hose to outlet fitting. Make sure cord is
pushed in as far as it can go to ensure a good
connection.
NOTICE
Piston and cylinder come
packaged together. Do NOT
let piston and cylinder come
apart. If they do, make sure
you drop the piston down
through the top of the cylinder
and tilt the piston as you pull
it through the cylinder. Do
NOT push the piston up from
the bottom. You could easily
damage the piston gasket. ti8943a
100
74
75
71
70
70
ti13414a ti13664a
ti13411a
ti13442a
ti13420a

4313768B
All written and visual data contained in this document reflects the latest product information available at the time of publication.
Graco reserves the right to make changes at any time without notice.
This manual contains English. MM 313768
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GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440-1441
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